Polyolefins are more lightweight and formable than metals or glass and excellent in appearance (transparency and gloss) and mechanical characteristics, and are hence applied widely as various industrial parts for automobiles, appliances, and the like.
However, since polyolefin products lack mar resistance, they are liable to surface damages (marring) by scuffing or scratching in some uses.
If an ultraviolet curable acrylic coating, such as polyester acrylate, urethane acrylate, and epoxy acrylate, which is generally applied to methacrylic resins or polycarbonate resins is coated on polyolefins and cured in an attempt to improve mar resistance of the polyolefins, sufficient adhesion cannot be achieved, failing to have practical utility.
Moreover, in cases where a coating is applied to three-dimensional parts, as are often used as industrial parts, to form a hard coat thereon, coating may be performed by spray-coating. However, spray-coating onto formed parts is accompanied by a great loss of the coating material and also finds difficulty in obtaining a smooth coated surface enough to give excellent gloss.
These problems might be avoided by thermoforming a sheet having an ultaviolet-cured hard coat. This technique however is of no utility because the hard coat having been previously undergone crosslinking fails to follow stretch of the sheet to cause cracking.